Product Courtesy of Hup Leong Company SRP: SGD58, Additional RDS cordless unit SDG45 Availibility: Now

Introduction of the company

Sigma is a German company, which started off making cycling computers since the 80s, and has been in operation for 20 years. They have revamped their whole range of cyclometer for 2003. Introducing the new Topline series, which boost technological innovations such as:
– Complete new supports for handlebar and stem mounting
– Full text display
– Easy, completely re-designed menu
– Correct, digital data-transmission with the RDS system

In the box

The standard BC-1600 package comes with a wired sensor unit. However, we are lucky to have the standard BC-1600 together with the optional RDS remote unit for review purpose. Inside the BC-1600 package is the cyclometer, 3 O-rings of different sizes, magnet, wired sensor/holder unit and the instructions. The optional RDS remote unit comes with another set of 3 O-rings, magnet, transmitting and receiving unit. Since the remote unit only comes as an optional item, this means that you will have spare O-rings and magnet if you decide to go cordless.

Mounting on the bike

The instructions are easy to follow and mounting the cyclometer onto the bike is a breeze, no tools are required. Everything is secured on the bike with the use of the O-rings and double-sided tape that are included in the package. For the magnet, simply clip it to the spokes and secure with the metal clip provided. Those using bladed spokes will need to get the special magnet elsewhere, as Sigma does not produce magnet that can be use with bladed spokes.

When mounting the unit, we were concern about the durability of the O-rings. They look sturdy, but are bound to disintegrate over time. Local weather does not help either. In addition, when cleaning the bike, ensure the chemical use will not damage the O-rings. It is advisable to check the O-ring from time to time for wear and tear. Replacement O-rings can be purchase from Hup Leong.

Unlike other cyclometer, the Sigma uses a unique twist and lock mechanism to mount the cyclometer onto its holder. This method not only offers better security against accidental release, it also seals the electrical contact points between the cyclometer and the holder against contaminants such as soil and dirt. Using the old slide in method, mud accumulated around the holder will eventually find their way to the contact points when the user attach or detach the meter from the holder. With the new method of attaching the cyclometer via the top, mud is kept away from the contact points, even during attachment and detachment.

Another plus point about the Sigma cyclometer is the versatile holder, which allows the user to rotate it at a 90 degrees angle, and can be mounted onto the handlebar or stem. This is good for those riders who have their handlebar packed with gadgets.

The cable that connects the cyclometer holder to the sensor is protected with re-enforced rubber casing. The thick rubber housing is built to withstand against accidental cuts and normal wear and tear. During the test period, one of the reviewers managed to snap the cable at its end when his hand got caught in them. However, we believe this to be an isolated case, and might not fairly reflect the quality of the cable.

Last but not least, the mounting of the RDS remote unit is also an easy task. When mounting, user just have to take note that the distance between the transmitter and receiver must be less than 70cm and the receiver must be above the transmitter, not more +/- 15 degree away vertically.


When using the Sigma, the most notable things are its big screen, full text display and easy-to-read font. It helps user to read the information in a quick glance. We can really feel the difference switching from our own meter to the Sigma.

In addition, while other manufacturers use a single button to access the entire sub-menu, Sigma divided its 12 sub-menu using two buttons. This allows the user quicker access to the sub-menu, and save the pain of pressing the button 11 times just to access the last sub-menu. Initially, we have problem remembering the correct buttons for the different sub-menu, but once familiar, most should appreciate the quicker access.

However, the Sigma lacks backlit display. This means the meter is hard or impossible to read during hours in the dark. We have a hard time reading the cyclometer even on local roads, which are well lit. To compensate for this, Sigma does produce a separate handlebar mount lighting system to be use with their range of cyclometer.

Another imperfection is that the actual speed on the Sigma is rounded off to the nearest 0.5 km/hr. It is not a problem for most riders, but this is a big turnoff for one of our reviewer who races. We would prefer the Sigma to increase the accuracy to the nearest 0.1 km/hr.

There are also several interesting new functions that other cyclometers might be missing.

-Permanent comparison of actual and average speed: – The cyclometer have a permanently indication on the screen which prompt you whether your current speed is below or above average for the trip. This will be useful for cyclists who are trying to beat their own average speed constantly.

-Separate trip riding time and stopwatch function: – Cyclometers usually have only one stopwatch function showing either the total riding time (total time the bike is in motion) or total trip time (total time from the start till the stop of the stopwatch). Interestingly, the Sigma provides its user with both the riding and trip time separately. This allows the user to know his total trip time, and how much of that time did he spend in motion.

-Reset each sub-menu individually or everything in a single button: – Sigma allows you to delete each sub-menu function individually. The next time you need to reset the trip meter and stopwatch you will still get to keep your maximum speed to show off to your friends.

-Settable trip segment (Moser Guide): – This function is useful for those who like to explore into the unknown. It works like a pacer, assisting the user to keep track of distance during navigation. Once activated, the Moser Guide will keep track of the distance travelled from the last confirm location or junction. When the user needs to back track, he can activate the countdown mode and the cyclometer will start counting down as the user ride. Moser Guide can only be use to trace the distance between two points at any one time. Hence, if you need to keep track of the distances for multiple waypoints, you will need to jot down the distance separately elsewhere.

Remote Digital System – RDS explained

We really like the RDS. In conventional analogue system, the sensor will sense the wheel’s rotation frequency and send the raw data to the cyclometer for processing. When interference from electronic equipment is present, the analogue signal might be distorted, thus resulting in absurd reading of speed being displayed on the cyclometer.

The RDS eliminate this problem by processing the raw data at the sensor itself, and send the processed data in a package to the receiver. By doing so, the data are protected against distortion. In the event that interference does affect the transmission of the data, the cyclometer will ignore the error data and display the last correct data available. This means that in the worst-case scenario, Sigma user will only get outdated data instead of erroneous ones. This is important for serious users who need to keep protect the integrity of their training data.

During testing, we actually place the bike next to a television set, computer, radio and even a handphone directly in the path of transmission. Amazingly, the Sigma holds on to its claims. Even when the transmitter is covered with thick mud, the transmission went on undisrupted.

While we really like the RDS, there are some trivial rants about it. In order for this sophisticated system to work, three batteries are needed as compared to the usual two for other cordless system. This translates to a teeny increase in maintenance cost.

In addition, the RDS receiver is mounted onto the holder via a simple slide-in mechanism. A light knock on it and it will fall off easily. During our three weeks of use, the receiver fell off three times, all during transportation of the bike.

After Thoughts

Just to summarise what we like and what we do not about the BC-1600:

1. Big screen display with large and easy to read font
2. 2 sub-menu buttons for quicker access
3. Versatile holder which allows mounting on handlebar or stem
4. Permanent comparison of actual and average speed
5. Separate trip riding time and stopwatch function
6. RDS system works even under strong electronic interference
7. Cable built to last
8. Optional cadence function

What we don’t:
1. No backlit display
2. Actual speed is rounded to the nearest 0.5 km/hr
3. Use of O-rings instead of conventional mounting brackets
4. Magnet cannot be use with bladed spokes
5. Cordless unit is only available as a upgrade option